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Proceedings Paper

Low-frequency magnetic and resistance noise in magnetoresistive tunnel junctions
Author(s): Lai Jiang; Jonathan F. Skovholt; Edmund R. Nowak; Jon M. Slaughter
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Paper Abstract

We report on the voltage fluctuations in exchange-biased, micron-scale magnetic tunnel junctions. We find that the spectral power density is 1/f-like at low frequencies and becomes frequency independent at high frequencies. The frequency-independent background noise is due to thermal and shot noise mechanisms. The nature of the 1/f noise has its origin to two different mechanisms. In the magnetic hysteresis loops this noise power is strongly field-dependent and is due to thermal magnetization fluctuations in both the 'free' and 'fixed' magnetic layers. We attribute these magnetic fluctuations to thermally excited hopping of magnetic domain walls between pinning sites. A second mechanism for the 1/f noise, connected with defects in the tunnel barrier but not related to the overall magnetization fluctuations, was found at fields for which the magnetic structure in the free and fixed layers is well aligned. This noise is associated with electron trapping processes having thermally activated kinetics and a broad distribution of activation energies. Below ~ 25 K the noise power is temperature independent suggesting that the kinetics are dominated by tunneling. Our results show that the thermal stability of the both magnetic layers and the quality of the tunnel barrier are important factors in reducing the low-frequency noise in magnetic tunnel junctions.

Paper Details

Date Published: 25 May 2004
PDF: 15 pages
Proc. SPIE 5469, Fluctuations and Noise in Materials, (25 May 2004); doi: 10.1117/12.544659
Show Author Affiliations
Lai Jiang, Univ. of Delaware (United States)
Jonathan F. Skovholt, Univ. of Delaware (United States)
Edmund R. Nowak, Univ. of Delaware (United States)
Jon M. Slaughter, Motorola, Inc. (United States)


Published in SPIE Proceedings Vol. 5469:
Fluctuations and Noise in Materials
Dragana Popovic; Michael B. Weissman; Zoltan A. Racz, Editor(s)

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